Towards personalised assessment of abdominal aortic aneurysm structural integrity

2025-02-14

AI Summary

Conventional abdominal aortic aneurysm (AAA) rupture risk assessment relies solely on diameter and growth rate, lacking patient-specific mechanical characterization. Method: We propose the Relative Structural Integrity Index (RSII), the first non-invasive, patient-specific, local structural integrity quantification method that requires no prior knowledge of material properties or wall thickness. RSII integrates dynamic strain measurements from 4D computed tomographic angiography (4D-CTA) with computational biomechanical inversion to enable spatially resolved wall tension–strain coupling analysis and mechanical state visualization. Contribution/Results: Validated in 12 patients, RSII demonstrates robustness and reveals significantly reduced local stiffness at the region of maximal dilation, while global wall stiffness remains elevated relative to healthy aorta—consistent with experimental literature. RSII transcends the “one-size-fits-all” diameter threshold paradigm, establishing a new framework for precision AAA risk stratification.

Technology Category

• Intelligent Robots: State Estimation
• Computer Vision: Medical and Biological Imaging
• Knowledge Representation and Reasoning: Diagnosis and Abductive Reasoning

Application Category

• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization

Abstract

Abdominal aortic aneurysm (AAA) is a life-threatening condition involving the permanent dilation of the aorta, often detected incidentally through imaging for some other condition. The standard clinical approach to managing AAA follows a one-size-fits-all model based on aneurysm size and growth rate, leading to underestimation or overestimation of rupture risk in individual patients. The widely studied stress-based rupture risk estimation using computational biomechanics requires wall strength information. However, non-invasive methods for local patient-specific wall strength measurement have not yet been developed. Recently, we introduced an image-based approach for patient-specific, in vivo, non-invasive AAA kinematic analysis using time-resolved 3D computed tomography angiography (4D-CTA) images to measure wall strain throughout the cardiac cycle. In the present study, we integrated wall tension computation and strain measurement to develop a novel measure of local structural integrity of AAA wall - Relative Structural Integrity Index (RSII), independent of material properties and thickness of the wall and conditions of blood pressure measurement. Our methods provide a visual map of AAA wall structural integrity for individual patients using only their medical images and blood pressure data. We applied our methods to twelve patients. Additionally, we compared our measure of structural integrity of aneurysmal and non-aneurysmal aortas. Our results show similar values of the wall structural integrity measure across the patients, indicating the reliability of our methods. In line with experimental observations reported in the literature, our analysis revealed that localized low stiffness areas are primarily found in the most dilated AAA regions. Our results clearly demonstrate that the AAA wall is stiffer than the non-aneurysmal aorta.

Problem

• Personalized assessment of AAA structural integrity needed
• Non-invasive wall strength measurement methods lacking
• Developed RSII for localized AAA wall analysis

Innovation

• 4D-CTA for AAA kinematic analysis
• RSII measures structural integrity
• Visual map from medical images